Help!!! Please!!!

[beatboxr21]

ok guys i need some advice!!! over the summer i built my motor with parts as listed
diamond forged pistons
comp cam vs cam
race bearings
zzp tune
headers
and remanufactured heads


she ran great the first time i started it up!! however i accidentally put in the oil pressure release valve in backwards and siezed a bearing to the crank.. so new bearings went in along with the crank. well we had problems with it because the cam sensor wires were cut open, it kept happening over and over so i cut and spliced them, and re routed the wires. the car has a huge leak from the back header to y pipe.. before o2 sensor.. cant plug it up and cant weld it.. so im goin through o2 sensors like crazy.. the car throws the o2 senor low circuit activity code MAF sensor low activity code and evap emissions purge solenoid.. ALL THREE PARTS ARE BRAND NEW!!! the car revs from 400 rpm to 1200 rpm at an idle.. already checked for vacuum leaks and couldnt find any. it is also only making 3 psi and should be just over 9 psi.. i really need help guys!!
thanks davie

[Fivefingerdeathpunch]

Sounds like a headache.

Id suggest you have a tuner on hand to really see what the car is doing.

[Poil336]

your exhaust leak is affecting your oxygen sensor readings. the oxygen sensor is the MOST important sensor for fuel delivery when you're in closed loop. you get a code from it because an oxygen sensor reads the difference between exhaust gas and atmospheric air. if it's reading atmospheric air, you get an incorrect reading. based on that incorrect reading, the pcm is chainging fuel trims, causing misfires and a rough idle. the sensor itself is fine. you won't be able to find a vacuum leak with any kind of brake clean check or something like that because you're already missing and your idle is trashed. fix your leak and go from there.

MAF sensor is the second most important sensor for fuel delivery. check your connectors. if the purge solenoid is stuck open and the vent solenoid is open, it's a vacuum leak in itself. the cam sensor determines which cylinder is on the compression stroke to determine which injector to fire. it'll work without it, but not well. to get what you want from it, all these need taken care of.

[Sven the Sexman]

Check fuses. You may have melted the one for the MAF. It's in the power distribution box under the hood.

EDIT: It said low activity, not no activity. My bad. I'd check for vacuum leaks. It's quite possible you shifted a gasket during the build.

[beatboxr21]

hey guys! thanks for the input!!
however i heard a knock from the top end so i checked out with a stethoscope and it sounded like the SC was knocking.. so i took the SC belt off to see if the noise stuck around and it did.. so now im going to check my compression in all six. ill keep you posted! thanks again!!